he highlighted the principal ways in which international law affected the course of action adopted: first, as a constraint, then as a basis of justification or legitimation of action, and third as providing organizational structures, procedures and forums. Because the presence of Soviet nuclear missiles in Cuba did not constitute an armed attack on the United States, warranting a more aggressive unilateral response, the Kennedy Administration imposed a naval quarantine on Cuba. This more restrictive response only blocked offensive military equipment from being imported. A classic blockade, on the other hand, restricts all imports, including food supplies, and is considered an act of war. Although the Soviet Union initially responded to the proposed quarantine by accusing the U.S. of “piratical acts” and “unheard of breaches of international law,” Washington lawyers took comfort in NATO support and a unanimous O.A.S. action authorizing the naval quarantine. By gaining the approval of the O.A.S. and using the unique forum of the United Nations for the crystallizing and mobilizing of national government views, the U.S. gained support and neutralized opposition during the crisis. In sum, Chayes noted the importance of the U.S. government's willingness to accept the obligation of international legal justification, and therefore, public accountability, during the successful mitigation of the Cuban Missile Crisis. In doing so, the role of international law in decision-making advanced. In 1968, Chayes, along with Thomas Ehrlich and Andreas Lowenfeld, formally introduced a new approach to the study of international law by publishing a two-volume textbook entitled: International Legal Process: Materials for an Introductory Course. The textbook focuses on three issue areas: 1) the limits of adjudication, 2) economic affairs, and 3) political problems, in order to provide a general introduction into the scope, adequacies and failures of an international legal system operating in a contemporary and complex international arena with new political actors, including a proliferation of international organizations. Each issue area contains problems that Chayes hoped would ignite classroom discussion and critical analysis, since, as he pointed out, most of these problems do not arise before courts or arbitral tribunals, but are debated by parties, under pressure from a variety of sources including NGOs and domestic lobbyists, during the policy decision-making process. Philip Heymann once said: “For Abe, problems were there to give joy to the people who tackled them.” Most recently, in his book The New Sovereignty: Compliance with International Regulatory Agreements, Chayes and Antonia